Primavera otoño 2020 (Año LXIII Núms. 122-123)

horizontes@pucpr.edu Año LXIV Núm. 124-125 horizontes PRIMAVERA / OTOÑO 2021 PUCPR 61 pathogens are found within the space between the plasma membrane and the cell wall. Improved detection of CLas at regional and seasonal levels should evaluate horizontally growing superficial fibers as opposed to deep vertical roots. The detection methods sampled roots grown in Texas, which were studied for three months, revealing they were asymptomatically infected trees. Louza-da et al. (2016) extracted DNA from the leaves and roots, which were dried at 60oC for one hour, with DNA extraction using a Qiagen DNeasy® kit. They used PCR amplification for each extract. Shallow roots were more infected than deeper roots, with root bacterial quantity declining distant from the trunk. Louzada et al. (2016) obtained detection rates of 96%. The early symptoms of HLB include yellowing of the leaves, followed by dieback of both the canopy and fibrous roots. Some fruits develop to be misshapen, green, and bitter. There is no cure for the HLB, and the infection is terminal. Barnett et al. (2019) studied the uncurable disease CLas, Huanglongbing, which affects the growth and defense of citrus plants and cost more than $4.5 billion loss of citrus in Florida, Texas, and California. They identified compounds to inhibit CLas activity by designing in vivo and in vitro studies to purify proteins to identify small molecule inhibitors of CLas. Improved detection of CLas at regional and seasonal levels should evaluate horizontally growing superficial fibers as opposed to deep vertical roots. Researchers revealed asymptomatically infected trees in Texas. There are no effective treatments for infected trees or resistant commercial citrus varieties; HLB can be managed mainly by controlling the spread of the Asian citri psyllid vector and replacing infected trees with uninfected nursery stock. CLas is a reduced genome that cannot be cultured. Silva et al. (2020) used genome sequence to report 36,702,109,559 base pairs were generated in 434,395,368 readings. The 9PA CLas strain genome sequence was assembled using reference mapping with CLC Genomics Workbench version 7.5 and Bowtie 2® systems using the CLas genomes. They used contagion information and prophage sequences in a conserved genetic region for the prophage to close gaps. A prophage was a bacteriophage genetic material included in the bacterium genome capable of producing phages. The sequence of the 9PA genome, including the two prophages, obtained 1,231,881 base pairs in 157 contigs (consensus regions) of more than 1,000 base pairs. The citrus rootstocks have been used for years to increase fruit production and quality. These rootstocks regulate the tree size and improve the tolerance to disease or pests. The sources of tolerance have been reported within the citrus pool. Bowman and Albrecht (2020) indicated differences in tolerance to CLas, including an increase without direct influence, influence to increase the tolerance against CLas of the stem or increase of general health not directly associated with CLas. Some of the HLB symptomatic leaves with chlorins and blotchy mott-ling are similar to leaves with nutritional deficiencies. Under low-nutrients conditions or stress, many plants can initiate senescence as a survival strategy to reallocate nutrients to the young tissues. Attaran et al. (2020) maintained citrus trees under conditions with natural light during March, June, and September for seasonal variability. Glucose was the most critical carbon source in the phloem, with increased leaf metabolites in Clas-infected citrus tissues exposed to glucose, indicating that the infection depends on seasonal metabolites and other nutrient variability. Detection of low titer CLas in early infected and asymptomatic samples becomes critical, the accurate detection of the low titer has a significant consequence for regulatory actions in California, with a management goal to