Genomic resources for the conservation of California native plants have gained increased attention recently; however, prior to our study, there were no Arctostaphylos glauca transcript data published that documented leaf and fruit RNAseq. The purpose of this study was to study functions of biotic and abiotic stress tolerance, including secondary metabolite production, that may make these plants more resilient.

Following RNA sequencing of the fruit and leaf tissues, quality control, assembly, and quantification, the plant transcripts were annotated with candidate genes from the best SProt BLASTX results. According to the BUSCO assessment, the transcriptome was 92.18% complete.

Phenylalanine ammonia lyase was closely related to the Camellia homolog (88.94% ID, TPM=29.59, length=2534). Similarly, Chalcone synthase 1 was related to Camellia (TPM=312.72, 95.61% ID, length=1596). There was also the indication that at least one Chalcone synthase transcript was related to Vitis (94.19% ID, length=1103, TPM=17.93). Chalcone–flavanone isomerase was 81.28% similar to Camellia (TPM=179.18, length=1059).

Anthocyanidin reductase ((2S)-flavon-3-ol-forming) was elevated, with its TPM (transcripts per million)=94.13 and length=1715. This transcript was most similar to Vitis. Several elevated transcripts were related to genes in Populus, including Trans-cinnamate-4-monoxygenase (TPM=68.19, length= 1979, 92.48% ID). Other interesting hits annotated from Populus were Caffeic acid 3-O-methyltransferase (TPM=96.34, length=1615, 82.09% ID) and Caffeoyl-CoA O methyltransferase (91.90% ID, length=1081, TPM= 55.50). Meanwhile, Flavanone-3-dioxygenase was most closely related to parsley (85.71% ID, TPM=53.03, length=1533).

There was also elevated expression of transcripts related to Hydroxyphenylpyruvate reductase in Plectranthus (80.51% ID, TPM= 70.71, length= 1767). Benzaldehyde dehydrogenase transcripts were elevated; the isoforms were most closely related to Antirrhinum (TPM= 42.63, length=1962, 82.49% ID).

There was evidence from multiple isoforms related to Arabidopsis of moderate expression of Plant cadmium resistance. There were several heat tolerance-related transcripts, such as Heat shock cognate 70 kDa protein 2, which was related to Solanum lycopersicon (96.60% ID, TPM=592, length=1018). These results provide insights into the diversity of manzanita genes related to antioxidant production and stress resistance.