A study on cassava tolerance to and growth responses under salt stress
A study on cassava tolerance to and growth responses under salt stress
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DOI：
10.1016/j.envexpbot.2018.07.022
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发表时间：
2018-11-01
影响因子：
5.7
通讯作者：
Li, You-Zhi
中科院分区：
文献类型：
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作者：
Cheng, Yan-E;Dong, Ming-You;Li, You-Zhi
土壤盐分通常以氯化钠为主，是粮食作物生产的主要制约因素。木薯是热带最重要的淀粉生产作物。据报道，该作物对盐胁迫中等敏感，A20/AN1型锌指基因可以赋予植物非生物胁迫耐受性，成为新兴的靶标基因。然而，无论是木薯的耐盐性，还是木薯A20/AN1型锌指基因对盐的反应都还没有得到详细的表征。在预先设定的0、10、20、30、40、50、100和200 mM盐浓度下，南中国124、福选01、南中国205、卡塞萨特50和阿根廷7号的耐盐性和贮藏根中淀粉含量略有不同。在本研究中，我们对这五个品种的试管苗的生长、激素、抗氧化酶、可溶性蛋白质和糖、过氧化氢含量以及A20/AN1型锌指基因的表达进行了研究。主要结果如下：木薯的生长受到明显的抑制，从20 mM的盐胁迫开始，不同品种的木薯生长受到抑制。5个品种在100 mM的盐胁迫下均不能生长；10 mM的盐通过增加须根的数目、体积、表面积、活力、须根长度和伸长的根细胞来促进生长；20 mM的盐促进须根中总淀粉的积累和地上部总蛋白质含量的增加；生长和淀粉积累的增加与激素水平无关，地上部和根间的抗氧化酶活性，甚至整个植株中的抗氧化酶活性都不相关；A20/AN1基因家族由至少11个成员组成，在200 mM的盐胁迫下，其在SC124试管苗中的表达受到诱导或抑制，这取决于基因成员。综上所述，低盐不仅促进了木薯的生长，而且促进了木薯须根中总淀粉的积累，提高了地上部总蛋白质的含量。低盐促进生长的作用可能与盐胁迫下较低水平的脱落酸、较高水平的赤霉素和吲哚-3-乙酸有关。这三种激素之间的拮抗关系可能与盐胁迫下A20/AN1基因的表达有关。在盐胁迫反应中对过氧化氢水平、渗透保护剂和抗氧化酶活性的需求取决于木薯品种。
Soil salinity, commonly dominated by NaCl, is a major constraint to the production of food crops. Cassava (Manihot esculenta) is the most important tropical starch-producing crop. Reportedly, this crop is moderately sensitive to salt stress, and the A20/AN1-type zinc finger genes can confer abiotic stress tolerance to plants as the emerging target genes. However, neither cassava tolerance to salt nor the response of A20/AN1-type zinc finger genes from cassava to salt has yet to be characterized in detail. South China 124 (SC124), Fuxuan 01, South China 205, Kasetsart 50 and Argentina 7 (C4), somewhat differ in salt tolerance and starch content in storage roots under pre-established NaCl concentrations of 0, 10, 20, 30, 40, 50, 100, and 200 mM. In this study, we investigated responses of in vitro-grown plantlets of these five cultivars, focusing on plantlet growth, phytohormones, antioxidant enzymes, soluble protein and sugar, H2O2 content, and expression of A20/AN1-type zinc finger genes. The major results were as follows: the growth of cassava was obviously inhibited, starting at 20 mM NaCl depending on the cultivars. All five cultivars could not grow at 100 mM NaCl; 10 mM NaCl caused promoted growth by increasing number, volume, surface area, viability, length of fibrous rootlets, and elongated root cells; 20 mM NaCl facilitated both accumulation of total starch in fibrous rootlets and increase in total protein content in shoots; increased growth and starch accumulation did not correlate with phytohormone levels, antioxidant enzyme activities between shoots and rootlets, or, consequently, in the whole plantlets; and the A20/AN1 gene family was composed of at least 11 members and their expression was induced or suppressed in rootlets of plantlets of pot-grown SC124 under 200 mM NaCl, depending on gene members. In conclusion, low salt (NaCl) can not only promote the cassava growth but also lead to accumulation of total starch in the fibrous rootlets and increase in total protein content in shoots instead of rootlets. Low salt promoting growth effects are likely associated with lower levels of abscisic acid and higher levels of gibberellin and indole-3-acetic acid under salt stress. Such antagonistic relationship among these three phytohormones maybe involves expression of A20/AN1 genes under salt stress. The demand for H2O2 levels, osmoprotectants, and antioxidant enzyme activities in salt stress responses is cassava cultivar-dependent.