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Rice prolamins are categorized into three groups by molecular size (10, 13, or 16 kDa), while the 13 kDa prolamins are assigned to four subgroups (Pro13a-I, Pro13a-II, Pro13b-I, and Pro13b-II) based on cysteine residue content. Since lowering prolamin content in rice is essential to minimize indigestion and allergy risks, we generated four knockout lines using CRISPR-Cas9, which selectively reduced the expression of a specific subgroup of the 13 kDa prolamins. These four mutant rice lines also showed the compensatory expression of glutelins and non-targeted prolamins and were accompanied by low grain weight, altered starch content, and atypically-shaped starch granules and protein bodies. Transcriptome analysis identified 746 differentially expressed genes associated with 13 kDa prolamins during development. Correlation analysis revealed negative associations between genes in Pro13a-I and those in Pro13a-II and Pro13b-I/II subgroups. Furthermore, alterations in the transcription levels of 9 ER stress and 17 transcription factor genes were also observed in mutant rice lines with suppressed expression of 13 kDa prolamin. Our results provide profound insight into the functional role of 13 kDa rice prolamins in the regulatory mechanisms underlying rice seed development, suggesting their promising potential application to improve nutritional and immunological value.

Species of the Asian genus Eotrechus Kirkaldy, 1902 (Hemiptera, Heteroptera, Gerromorpha, Gerridae, Eotrechinae) are atypical water striders because they live on the near-vertical rock surfaces of waterfalls. The taxonomy of the genus is revised and six new species are described: E. steineri sp. nov., E. kerberos sp. nov., E. thai sp. nov., E. konkakinh sp. nov., E. boukali sp. nov., and E. anderseni sp. nov. Supplementary descriptions of the apterous female and macropterous male of E. fuscus Basu, Chandra & Venkatesan, 2017 are provided. Additional and updated distribution data of species of Eotrechus are reported. Eotrechus fuscus is reported from Myanmar for the first time; E. brevipes is reported from Nepal for the first time; E. hygropetricus Andersen, 1982 is reported from southern Thailand for the first time, which extends the southernmost limit of the known distribution of the genus. A revised key to the species of Eotrechus is also provided.

The species of Rhyacobates Esaki, 1923 are reviewed. Three new species, R. bui sp. nov. from Guangxi, China and Lạng Sơn, Vietnam, R. elongatus sp. nov. from Hà Tĩnh, Vietnam and R. turgidus sp. nov. from Sichuan and Chongqing, China are described. Supplemental descriptions, diagnoses and new distribution records are provided for the fourteen previously known species, i.e., R. abdominalis Andersen & Chen, 1995, R. anderseni Tran & Yang, 2006, R. angustus Tran & Nguyen, 2016, R. chinensis Hungerford & Matsuda, 1959, R. constrictus Tran & Nguyen, 2016, R. edentatus Andersen & Chen, 1995, R. gongvo Tran & Yang, 2006, R. lundbladi (Hungerford, 1957), R. malaisei Andersen & Chen, 1995, R. recurvus Andersen & Chen, 1995, R. scorpio Andersen & Chen, 1995, R. svenhedini (Lundblad, 1934), R. takahashii Esaki, 1923, and R. zetteli Tran & Nguyen, 2016. Photographs and line drawings of the habitus, diagnostic characteristics of both sexes, the habitat and in-situ photographs are presented. A revised key to the species of Rhyacobates is also provided.

The taxonomy of Micronectidae in Vietnam is reviewed. Based on our cumulative collections during 2001–2020, 11 new species of Micronecta Kirkaldy, 1897 are documented and described in this study: M. acuminata sp. nov., M. arcuata sp. nov., M. caperata sp. nov., M. clavata sp. nov., M. cultellata sp. nov., M. fulvopicta sp. nov., M. nieseri sp. nov., M. pingae sp. nov., M. sinuata sp. nov., M. undulata sp. nov., and M. vietnamica sp. nov. Nine species are recorded from Vietnam for the first time: M. decorata Lundblad, 1933, M. drepani Nieser, 2000, M. erythra Nieser, Chen & Yang, 2005, M. fugitans Breddin, 1905, M. johorensis Fernando, 1964, M. melanochroa Nieser, Chen & Yang, 2005, M. ornitheia Nieser, Chen & Yang, 2005, M. sahlbergi (Jakovlev, 1881), and M. tuwanoni Nieser, Chen, Leksawasdi, Thanyakam & Duangsupa, 2004. Thus, in this study, two genera and 37 species of Micronectidae are now reported from Vietnam: Synaptonecta Lundblad, 1933 with only one species, S. issa (Distant, 1910), and Micronecta with 36 species. A key to all species occurring in Vietnam, subgeneric diagnoses, and a key to all current subgenera of Micronecta are provided.

Saltwater intrusion is a potential risk damaging crop diversity and productivity due to degraded soil physicochemical properties. However, little is known about how salinity affects the structure and function of soil nematodes community in intensive rice cultivated area. This study aimed (1) to assess the impacts of saltwater intrusion on the nematode community in alluvial and acid sulfate soils; and (2) to evaluate its relation with soil conditions. Saltwater intrusion reduced the abundance of both free-living nematodes (FLN) and plant-parasitic nematodes (dominated by Hirschmanniella) in soils. FLN community was different among sites with different physicochemical properties. The omnivorous genera Aporcelaimellus and Thornenema were only found in non-salt-affected alluvial soil, whilst Mesodorylaimus was dominant in salt-affected acid sulfate soil, suggesting that this genus might be tolerant to higher EC and soluble Na+, K+, Ca2+. The bacterivorous nematodes (dominant taxa Chronogaster, Rhabdolaimus) were dominant in both non-salt affected and salt-affected alluvial soils, which accounted for 48% and 40%, respectively, whilst it accounted for 21% in salt-affected acid sulfate soil. The abundance of fungivorous nematodes (Aphelenchoides, Ditylenchus, Filenchus) were greater in salt-affected alluvial soil in contrast to the other treatments, suggesting that these might be tolerant to salinity and low pH. Saltwater intrusion reduced biological diversity (Margalef, Shannon-Wiener, and Hill’s indices), maturity index (∑MI, MI25), and clearly affected functional guilds of nematode community, especially c-p 5 group was reduced in both salt-affected soils. This study suggests that saltwater intrusion showed a potential risk in the degradation of soil properties, as indicated by the altered nematode community, trophic structure, functional guilds and their ecological indices in paddy fields.

An integration of a shrimp production cycle into the traditional system of rice farming is an adopted practice by farmers due to saline intrusion and changes of environmental condition in Vietnam. Aquacultural pond sludge or biological waste has the potential to cause environmental pollution if it is not managed well. However, the sludge from shrimp ponds in rice-shrimp farming systems can provide nutrition and maintain soil fertility for the integrated rice crop production. A randomized block field experiment was conducted on a rice-shrimp farm to test the fertilizer value of sludge for rice over two consecutive seasons in Vietnam. Five treatments of sludge and fertilizer rates were applied in field experiments including control, sludge application alone, recommended fertilizer rate, reduced fertilizer rate, and combination of sludge and reduced fertilizer rate. The results consistently proved that the pond sludge can provide large quantities of plant available nutrients such as ammonium nitrogen, total nitrogen and organic matter. The use of sludge either alone or in combination with the reduced fertilizer rate produced optimal rice yields while fertilizer cost of rice production was reduced. This finding indicates that the use of sludge is able to save cost of production to rice-shrimp farmers and reduce adverse impacts of pond sludge released on the surrounding environment.