Table_3_Volatile profiling as a potential biochemical marker for validation of gamma irradiation derived putative mutants in polyembryonic genotypes of mango (Mangifera indica L.).docx

IntroductionPutative mutants were generated through gamma irradiation in the polyembryonic mango genotype Nekkare. The putative mutant progenies along with control seedlings and mother plants were evaluated by comparing the compositions and relative proportions of their major volatile compounds.MethodsVolatile profiling was done using headspace-solid phase micro-extraction (HS SPME) method coupled with gas chromatography–mass spectrometry (GC-MS MS). Furthermore, characterisation of putative mutants and control seedlings was carried out using simple sequence repeat (SSR) markers to ascertain the genetic diversity present in the samples under study.ResultsMonoterpenes were the most abundant volatile compound in all the studied samples (ranging from 34.76% to 91.41%) out of which I-Phellandrene and cis-Ocimene formed the major fraction in mother plants (20.45%–21.86% and 16.17%–21.27%, respectively) and control seedlings (23.32%–24.95% and 18.95%–20.81%, respectively), while beta-Phellandrene was dominant in the selected putative mutant samples (2.34%–29.53%). Among sesquiterpenes, trans-Caryophyllene was detected only in the putative mutant samples (0.10%–30.18%). Grouping together of mother plants and control seedlings was seen in the cluster analysis, while the putative mutants grouped apart from them suggesting genetic diversity. Genetic distance between the mother plants and control seedlings ranged from 0.97 to 2.73, while between putative mutants, control seedlings, and mother plants, it ranged from 6.54 to 9.82. SSR-based characterisation of putative mutant seedlings showed that mutation caused variability in the treated population. This was evident from the high allelic richness ranging from 4 to 12 with a mean of 7 and a higher mean Shannon’s Information Index (1.50) of the putative mutant population.DiscussionThe study demonstrates that volatile profiling and molecular characterisation using SSR markers could be used as a tool to detect variation in a mutated population. In addition, volatile profiling can be used to validate putative mutants in polyembryonic mango genotypes where the seedlings of nucellar origin are similar to mother plants.

本研究通过γ射线照射多胚芒果基因型Nekkare，生成假设性突变体。将假设性突变后代、对照种子和母本植株通过比较其主要挥发性化合物的组成和相对比例进行评估。研究方法采用顶空固相微萃取（HS-SPME）法结合气相色谱-质谱联用（GC-MS MS）进行挥发性分析。此外，利用简单序列重复（SSR）标记对假设性突变体和对照种子进行表征，以确定研究样本中的遗传多样性。结果显示，单萜类化合物在所有研究样本中含量最为丰富（34.76%至91.41%），其中对-桉油醇和顺式-香茅醇在母本植株（20.45%–21.86%和16.17%–21.27%）及对照种子（23.32%–24.95%和18.95%）中占主要比例，而β-桉油醇在选定的假设性突变样本中占优势（2.34%–29.53%）。在倍半萜类化合物中，仅检测到反式-石竹烯存在于假设性突变样本中（0.10%–30.18%）。聚类分析显示，母本植株和对照种子聚为一组，而假设性突变体则与之分离，表明存在遗传多样性。母本植株与对照种子之间的遗传距离在0.97至2.73之间，而假设性突变体、对照种子和母本植株之间的遗传距离在6.54至9.82之间。基于SSR的假设性突变种子表征表明，突变导致了处理群体中的变异。这从处理群体中高等位基因丰富度（4至12，平均值为7）以及假设性突变群体较高的平均香农信息指数（1.50）中得以体现。讨论部分指出，通过挥发性分析及SSR标记的分子表征可以作为检测突变群体中变异的工具。此外，挥发性分析还可用于验证多胚芒果基因型中的假设性突变体，其中核源种子与母本植株相似。