Author: Karla Gabriela Huerta AcostaPublisher:
ISBN:
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Languages : en
Pages : 0
Book Description
Six groups were identified using the STRUCTURE software and were named according to the region where most of the accessions originated: Eastern, Northeastern, Central, Coahuila, Chihuahua, and Western Mexico groups. The Trans-Mexican Volcanic Belt biogeographic province was the area with the greatest Vitis diversity. The most abundant species found were V. arizonica in the north and V. cinerea in Central Mexico. Moreover, V. bloodworthiana was identified to the west and V. tiliifolia to the east. Samples collected by Dr. Olmo in the 1960s were also added to the study, and it was found they were the most diverse accessions. This finding highlighted the importance of Vitis collection, as diversity reduction was evident from these two collection periods. This chapter was very important as it emphasizes the relevance of Mexican Vitis conservation. It is our group's intention to maintain the collaboration with the involved Mexican institutions to evaluate the accessions phenotypically and identify possible traits useful for breeding. Xylella fastidiosa has been extensively studied to understand its pathobiology and find new ways to control it. Scientists have focused on the creation of mutants to pinpoint specific gene functions that might help control infection. A secretome study was conducted in Dr. Dandekar's lab, where X. fastidiosa secreted proteins were identified that may have a role in infection. In order to understand its upregulation and interaction with the host, a X. fastidiosa mutant with a protease (prtA-) disrupted gene was created. In their study, the prtA- mutant was tested in V. vinifera cv. Thompson Seedless. Due to its rapid symptom onset, the prtA- mutant was classified as a hypervirulent strain. Inoculation in Thompson Seedless gave limited information about the mutant's performances; thus, Chapter 4 focused on prtA- disease assessment trials of genotypes with a wide range of PD susceptibility, going from highly resistant wild grapevines to susceptible V. vinifera like Chardonnay. In addition, prtA- was inoculated in PD resistant accessions T03-16, b40-14, b46-43, and b42-26 to see if they maintained their resistance and as an opportunity to elucidate their mechanism of resistance. After statistical analyses, it was observed that prtA- did not perform as expected. It was expected that prtA- would cause more severe symptoms when compared to the wildtype Tem1. However, neither of the strains caused symptoms in the cane, which is typically affected by X. fastidiosa. Results showed resistant accessions and tolerant genotypes were resistant to prtA-, and susceptible genotypes were susceptible. Thompson Seedless was the most susceptible genotype of those tested, followed by Chardonnay. The typically susceptible genotype U0505-22, was surprisingly resistant to prtA-, suggesting it can recognize it and stop colonization. Because resistant accessions performed the same when inoculated with the wildtype strains, no mechanism of defense was elucidated. However, it was hypothesized anatomical differences in the tested genotypes played an important role in speeding symptom onset. This chapter was a collaboration with Dr. Abhaya Dandekar's lab, specifically with the graduate student Cintia Helena Duarte Sagawa. These chapters contribute to the study of control measures to combat X. fastidiosa and further document our exploration of genetic sources of resistance.
