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Xyloglucan endotransglycosylase/hydrolase (XTH) genes play an important role in plant resistance to abiotic stress. However, systematic studies of the response of Boehmeria nivea (ramie) XTH genes (BnXTHs) to cadmium (Cd) stress are lacking. We sought to identify the BnXTH-family genes in ramie through bioinformatics analyses and to investigate their responses to Cd stress. We identified 19 members of the BnXTH gene family from the ramie genome, referred to as BnXTH1-19, among which BnXTH18 and BnXTH19 were located on no chromosomes and the remaining genes were unevenly distributed across 11 chromosomes. The 19 members were divided into four groups, Groups I/II/IIIA/IIIB, according to their phylogenetic relationships, and these groups were supported by analyses of intron–exon structure and conserved motif composition. A highly conserved catalytic site (HDEIDFEFLG) was observed in all BnXTH proteins. Additionally, three gene pairs (BnXTH6–BnXTH16, BnXTH8–BnXTH9, and BnXTH17–BnXTH18) were obtained with a fragment and tandem-repeat event analysis of the ramie genome. An analysis of cisregulatory elements revealed that BnXTH expression might be regulated by multiple hormones and abiotic and biotic stress responses. In particular, 17 cisregulatory elements related to abiotic and biotic stress responses and 11 cisregulatory elements related to hormone responses were identified. We also found that most BnXTH genes responded to Cd stress, and BnXTH1, BnXTH3, BnXTH6, and BnXTH15 were most likely to contribute to the Cd tolerance of ramie, as evidenced by the substantial increases in expression under Cd treatment. Heterologous expression of BnXTH1, BnXTH6, and BnXTH15 significantly enhanced the Cd tolerance of transgenic yeast cells. These results suggest that the BnXTH gene family is involved in Cd stress responses, laying a theoretical foundation for functional studies of BnXTH genes and the innovative breeding of Cd-tolerant ramie.

The Qinghai-Tibetan Plateau is a large and elevated plateau (mean elevation 4500 m) in northwestern China, where with a harsh environment for animal survival. Tibetan sheep is an important dominant livestock that inhabit this harsh environment. The objective of this trial was to preliminarily explore and compare the effects of indigenous barley straw (BS) and artificial cultivated oat hay (OH) on growth performance, visceral organ mass and meat quality of Tibetan sheep. Twenty-four Tibetan sheep with initial weights of 15.9±1.92 kg were randomly assigned to two mixed diets containing the same concentrate mixed with BS or OH, and the experiment was carried out in a completely randomized design. The weight of lungs and thymus for OH was greater (P≤0.05) than that of BS, while the weight of other viscera (heart, liver, kidney, epinephros and spleen) had no significant difference (P>0.05) between the two. The weight of the rumen, reticulum and abomasum for OH was 10.31%, 31.22% and 33.44% (P≤0.01) higher than that of BS. The length of the colon in sheep fed OH diet was longer (P≤0.01) than the sheep fed BS diet. The content of Histidine in longissimus dorsi muscle of OH was greater (P≤0.05) than that of BS, while there were no significant (P>0.05) differences between the two for the other individual amino acids (AA), umami AA, essential AA and total AA. It is concluded that the two types of roughage did not affect the growth and slaughter performance, meat quality, but OH is beneficial for the gastrointestinal development for Tibetan sheep.