Backiyarani S, Uma S, Nithya S, Chandrasekar A, Saraswathi M S, Thangavelu R, Mayilvaganan M, Sundararaju P, Singh N K
ICAR-National Research Centre for Banana, Thogmalai Road, Thayanur Post, Trichy, 620102, Tamil Nadu, India,
Appl Biochem Biotechnol. 2015 Apr;175(8):3585-98. doi: 10.1007/s12010-015-1528-z. Epub 2015 Feb 10.
Knowledge on structure and conserved domain of Musa chitinase isoforms and their responses to various biotic stresses will give a lead to select the suitable chitinase isoform for developing biotic stress-resistant genotypes. Hence, in this study, chitinase sequences available in the Musa genome hub were analyzed for their gene structure, conserved domain, as well as intron and exon regions. To identify the Musa chitinase isoforms involved in Pratylenchus coffeae (root lesion nematode) and Mycosphaerella eumusae (eumusa leaf spot) resistant mechanisms, differential gene expression analysis was carried out in P. coffeae- and M. eumusae-challenged resistant and susceptible banana genotypes. This study revealed that more number of chitinase isoforms (CIs) were responses upon eumusa leaf spot stress than nematode stress. The nematode challenge studies revealed that class II chitinase (GSMUA_Achr9G16770_001) was significantly overexpressed with 6.75-fold (with high fragments per kilobase of exon per million fragments mapped (FPKM)) in resistant genotype (Karthobiumtham-ABB) than susceptible (Nendran-AAB) genotype, whereas when M. eumusae was challenge inoculated, two class III CIs (GSMUA_Achr9G25580_001 and GSMUA_Achr8G27880_001) were overexpressed in resistant genotype (Manoranjitham-AAA) than the susceptible genotype (Grand Naine-AAA). However, none of the CIs were found to be commonly overexpressed under both stress conditions. This study reiterated that the chitinase genes are responding differently to different biotic stresses in their respective resistant genotypes.
了解香蕉几丁质酶同工型的结构和保守结构域及其对各种生物胁迫的反应，将有助于选择合适的几丁质酶同工型，以培育抗生物胁迫的基因型。因此，在本研究中，对香蕉基因组中心中可用的几丁质酶序列进行了基因结构、保守结构域以及内含子和外显子区域的分析。为了鉴定参与抗咖啡短体线虫（根腐线虫）和香蕉黑星病菌（香蕉叶斑病）机制的香蕉几丁质酶同工型，在受到咖啡短体线虫和香蕉黑星病菌侵染的抗性和感病香蕉基因型中进行了差异基因表达分析。本研究表明，与线虫胁迫相比，香蕉叶斑病胁迫下有更多的几丁质酶同工型（CIs）做出反应。线虫侵染研究表明，在抗性基因型（Karthobiumtham - ABB）中，II类几丁质酶（GSMUA_Achr9G16770_001）显著上调表达，是感病基因型（Nendran - AAB）的6.75倍（每百万映射片段中外显子每千碱基片段数（FPKM）高）；而当接种香蕉黑星病菌时，在抗性基因型（Manoranjitham - AAA）中，有两种III类CIs（GSMUA_Achr9G25580_001和GSMUA_Achr8G27880_001）上调表达，高于感病基因型（大奈蕉 - AAA）。然而，在两种胁迫条件下均未发现有共同上调表达的CIs。本研究重申，几丁质酶基因在各自的抗性基因型中对不同的生物胁迫反应不同。
