Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA.
Texas A&M AgriLife Research, Corpus Christi, TX, USA.
Sci Rep. 2020 Dec 18;10(1):22320. doi: 10.1038/s41598-020-79473-x.
Basal leaf angle distribution was surveyed in twenty-one Johnsongrass cultivars near the end of the vegetative stage. The angles increased from the top to the bottom leaves, and compared to cultivated grain sorghums, the average angle was larger in Johnsongrass. When basal leaf angle distribution data were correlated with pathogenicity test data from excised-leaf assays for three isolates of Colletotrichum sublineola, the results showed a weak positive correlation between basal leaf angle and pathogenicity level in Johnsongrass. In order to investigate a protective role of leaf thickness to C. sublineola, leaf thickness was measured in three sorghum cultivars and one Johnsongrass cultivar at the 8-leaf-stage. Leaf thickness near the apex, near the base, and half-way between the two points were measured in the top four leaves of each plant. Thickness of leaf blade and midrib were recorded separately. Using an excised-leaf-assay, the three points were inoculated with C. sublineola, and pathogenicity level was recorded 4-days-post-inoculation. Results showed strong negative correlations between leaf midrib thickness and pathogenicity level in sorghum and Johnsongrass but not in leaf blades.
在营养生长末期，对 21 个约翰草品种的基生叶角度分布进行了调查。叶片从顶部到底部的角度逐渐增大，与栽培的高粱相比，约翰草的平均角度更大。当基生叶角度分布数据与 3 种炭疽菌分离物的离体叶片致病性试验数据相关联时，结果表明约翰草的基生叶角度与致病性水平之间存在微弱的正相关。为了研究叶片厚度对炭疽菌的保护作用，在三叶期测量了 3 个高粱品种和 1 个约翰草品种的叶片厚度。在每个植株的前 4 片叶中，测量了叶片顶部、底部和两点之间的近尖端、近基部和中间位置的叶片厚度。分别记录叶片和中脉的厚度。采用离体叶片接种法，将三点接种炭疽菌，4 天后记录致病性水平。结果表明，在高粱和约翰草中，叶片中脉厚度与致病性水平呈强负相关，但在叶片上则不相关。
