Prolonged far red irradiation of imbibed lettuce seeds (Lactuca sativa L. cv. Grand Rapids) makes them unresponsive to subsequent treatment with gibberellin. It has been found that this effect is overcome by supplying gibberellin buffered at a low pH. On the basis of this and other evidence it is suggested that an extended far-red exposure causes a loss of gibberellin sensitivity through an eff...

Resistance Gene Candidate2 (RGC2) genes belong to a large, highly duplicated family of nucleotide binding site-leucine rich repeat (NBS-LRR) encoding disease resistance genes located at a single locus in lettuce (Lactuca sativa). To investigate the genetic events occurring during the evolution of this locus, approximately 1.5- to 2-kb 3' fragments of 126 RGC2 genes from seven genotypes were seq...

A soilborne disease of lettuce, associated with necrosis and dieback, has been found with increasing frequency in California and Arizona over the last 10 years. An isometric virus, serologically related to Tomato bushy stunt virus (TBSV), was consistently isolated from lettuce plants with these disease symptoms. Back-inoculation to healthy lettuce plants and subsequent reisolation of the virus ...

To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with r...