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Leaves are the main site of photosynthesis in plants, and leaf color plays a major role in crop quality, yield, resistance, as well as other aspects. Although the genes related to photosynthesis have been well characterized in plants in general, yellow-green leaf mutants have not yet been fully studied in tomatoes. In the present study, a dark green leaf (GL) mutant was isolated from yellow-leaf tomato (wild-type). The dark GL displays a distinct yellow-green phenotype, and has a greater chlorophyll content and higher photosynthetic rate. Furthermore, the lamellae were clear, and the stroma and grana were orderly, with more stacking and larger starch grains according to the ultrastructure analysis of chloroplasts in GL leaves. Comparative transcriptome analysis of GL and wild-type plants was performed to identify the pathways and genes related to photosynthesis. In this work, a total of 292 differentially expressed genes (DEGs) between GL plants and WT plants were identified, of which 131 genes were upregulated and 161 genes were downregulated. The diterpenoid biosynthesis and photosynthesis antenna proteins were the two most significantly enriched in the first 20 pathways according to KEGG analysis. Most of the DEGs involved in diterpenoid biosynthesis and photosynthesis were antenna proteins. The photosynthesis antenna protein Solyc02g071030 (LHCB1) and the diterpenoid biosynthesis-related genes, Solyc08g005710 and Solyc09g059240, were significantly upregulated in GL leaves compared with WT leaves. The expression patterns of the DEGs were similar to those determined by qRT-PCR. Overall, our research not only revealed the diterpenoid biosynthesis and photosynthesis pathways involving in leaf color variation, but also identified the putative target genes for genetic manipulation in the future. [ABSTRACT FROM AUTHOR]

Previous studies have shown that WRKY transcription factors play important roles in abiotic stress responses. Thus, virus-induced gene silencing (VIGS) was used to identify the function of SlWRKY79 in the salt tolerance of tomato plants by downregulating the expression of the SlWRKY79 gene. Under the same salt treatment conditions, the SlWRKY79-silenced plants showed faster stem wilting and more severe leaf shrinkage than the control plants, and the bending degree of the stem of the SlWRKY79-silenced plants was also greater than that of the control plants. Physiological analyses showed that considerably higher levels of hydrogen peroxide (H2O2), superoxide anion (O2−), and abscisic acid (ABA) accumulated in the leaves of the SlWRKY79-silenced plants than in those of the controls after salt treatment. Taken together, our results suggested that SlWRKY79 plays a positive regulatory role in salt tolerance in tomato plants. [ABSTRACT FROM AUTHOR]

Heterosis and combining ability are two important considerations in the utilization of heterosis, which can be used to generate excellent hybrid resource candidates and is very important in conventional hybrid breeding. In this study, the combining ability, heritability, and heterosis of eight major agronomic traits were analyzed in 10 tomato parents and 45 crosses between them. As well as TY-301, a recognized and official excellent variety that is currently selling well on the market was used as a control to conduct a control heterosis analysis, with the goal of selecting ideal parents with high combining ability and new hybrids with commodity value, high yield, early maturity, and high quality. The results showed that both additive and nonadditive genetic effects are involved in the expression of the traits and that the additive genetic effect is dominant in trait inheritance. Although general combining ability (GCA) and specific combining ability (SCA) were not correlated, and the strength of heterosis depends on SCA, the sum of the parental GCA values (GCAsum) did predict heterosis for some traits with higher predictive accuracy than did SCA. Compared with heterosis, GCAsum can better predict hybrid performance. Finally, the parent 17,969 was the breeding material with the best comprehensive trait performance, especially in yield. We screened a high-yielding candidate combination 17,927 × 17,969 and a precocious and good taste candidate combination 17,666 × 17,927. This information may play an important role in the selection of superior parents and hybrid combinations based on combining ability and heterosis analysis. [ABSTRACT FROM AUTHOR]